Propeller pitch changing mechanism



Dec. 4, 1951 c. w. CHILLSON 2,577,604

PROPELLER PITCH CHANGING MECHANISM Filed July 23, 1947 11 Sheets-Sheet 1Jnvcntor .(7mI'Ze5 W (77115012 Gttorncg Dec. 4, 1951 c. w. CHILLSONPROPELLER PITCH CHANGING MECHANISM 11 Sheets-Sheet 2 Filed July 25, 1947Ihwcutor (72617125 W (7117/5072 dttormu Dec. 4, 1951 c. w. CHILLSONPROPELLER PITCH CHANGING MECHANISM ll Sheets-Sheet 3 Filed July 23, 1947Ennentor 672617165 W (7117/5071 Gttorneg 1951 c. w. CHILLSON 0 PROPELLERPITCH CHANGING MECHANISM Filed July 25, 1947 I ll Sheets-Sheet 4 I I E 7H6 5?:4 \2 l "I I l l I I. l

INVENTOR.

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BY "WKW ATTORNEY- Dec. 4, 1951 c w, c sc 2,577,6Q4

PROPELLER PITCH CHANGING MECHANISM Filed July 25. 1947 ll Sheets-Sheet5' L L Fig.5

INVENTOR. d/zarZes WflZiZLiO/Z Dec. 4, 1951 c. w. CHILLSON PROPELLERPITCH CHANGING MECHANISM l1 Sheets-Sheet 6 Filed July 23, 1947 INVENTOR.Uzarles W 672115012 BY ATTORNEY Dec. 4, 1951 c. w. CHILLSON PROPE LLLERPITCH CHANGING MECHANISM ll She ets-Sheet 7 INVENTOR. d ariesWC/zz'ZLm/z A TTOKNE Y Filed July 23, 1947 Dec. 4, 1951 c. w. CHILL'SONPROPELLER PITCH CHANGING MECHANISM ll Sheets-Sheet 8 Filed July 25, 1947INVENTOR.

Dec. 4, 1951.

Filed July 25, 1947 T0 CLUTCH no DEERE/15 E T0 CLUTCH H2 70 aura/7 n4 T0CL UTCH I30 LOW SPEED T0 CLUTCH 12o MED/UM SPEED F-g. l3

BIO 320 11 Sheets-Sheet 10 322 I [j F/X P/TC/Y [I HIGH C DECREASE [hHIGH I C INCREA SE [h NED/UM DECREASE MED/UM INCREASE LOW DECREASE LOWlA/C/FEASE INVENTOR.

'CHA RLEJ M CHILLSOA,

ATTORNEY Patented Dec. 4, 1951 2571604. PROPELLER rrron CHANGINGMECHANISM Charles W1 'Chill'son Galdwell, N. 1.,assignor't0': oration,a: corporation: of:

Curti'ss Wright Corp Delaware:

Application Jill'y 23.1947, Serial No. 762,853

This invention relates to variable pitch propellers and moreparticularly to propellers inwhich power for" pitch change is primarilyderived from the-propeller drive shaft.

in variable pitch propellers foraircraft, the minesresisting'the'changing'of' pitch of the propeller blades; for exampleaerodynamic twisting. moments, centrifugal twisting moments and frictionare of sufiicient magnitude to require a large amount-o1 power whererapid change of pitch is desired. Where the propeller pitch is" to bereversed as for braking purposes, it isd'esirable that the pitchreversal take'place'in a relatively short interval of time; since thepropellerin approaching zero or flat-pitch relieves the prime movermomentarily of substantiallyits entire load, there:- by providing anopportunity for overspeeding; A propeller which is adapted to operate inreverse pitch as a brake may through pitch variation, control the speedof its driving pri'memover, and tlieirate of pitch changefor-suchcontrol is necessarily preferably slow. Propellers operating'in reversepitch when employed to control prime mover speed through pitch variationexhibit a high degreeof sensitivity; that is; a relativelysmall pitchchange may elrect a great. change. in engine load ing; Consequently, therate of pitch change of a propeller in reverse pitch While braking mayto advantage be made at a speed much less than that employed for speedgoverning purposes in the positive range: Very fast change of pitch isdesirablefor-the purpose of feathering a propeller quickly in the" eventthe prime mover should fail. as a sourceofpowen.

It is' accordingly an object of the. presentinvention to provide avariable pitch propeller wherein pitch change power mechanically derivedfrom the propeller drive shaft andin which the power so derived may bedelivered. to the. propeller for pitch increase or decrease at vary.-in'g'rates of speed selectable at will. 7

Another object of the invention is. to provide in a mechanism of. theaioresaid. type a structural arrangement of. the parts. such. that thegearing adapted to derive power from. the propeller shaft is arrangedlaterally of and. around; the drive shaft, so that inspection. andreplace ment may not require. dismantling of. the. propell'er or' itsdrive shaft.

Afurther object of. the. invention. is to provide in a mechanism oi the.type. described a dual planetary gear train. arranged'laterally of the.propeller. shaft by means of which. power may be: derived from thepropeller shaft and delivered to the pro eller pitch changing mechanism.to.

6"Olai-ms; Cl. ITO-160.28)

increase or decrease pitch at varying rates of speed.

' Still another object of the invention is to provide a mechanicalvariable pitch propeller in which pitch varying power' or holding torqueis continuouslytransmi'tted during propeller operation.

The above and other novel features of" the invention will appearmore-fully hereinafter from the following detailed description whentaken in conjunction with the accompanying drawings. It is expresslyunderstood, however, that thedrawings are employed for purposes ofillustration only and are not designed as a definition of the limits of"the invention, reference being had for'thispurpose to the appendedclaims.

In the drawings, wherein like reference characters indicatel'ike parts;

Fig: 1 is a side elevation of a propeller having oneform of pitchchanging mechanism, with parts thereof shown in section; V

Fig. 2 is a section taken substantially on the line 2-2 of Fig. 1;

Fig. 3' is a; section taken substantially on the line 3'3 of Fig. 1;

Fig. 4 is a schematic diagram of the gear trains of the modification ofFigs. 1-4, laid out in a plane;

Fig. 5 is a side elevation of a propeller partlyin section showing amodified form of pitch changing mechanism;

Fig. 6 is a section taken substantially on the line 6-6 ofFi'g. 5';

Fig; 7 is a section taken substantially on the line 1--1 of Fig. 5'; I

Fig. 8 is a longitudinal section taken through a lay shaft substantiallyon the line 8'8 of Fig. 6;

Fig. 9 is a section taken on another lay shaft substantially on the line9-9 of Fig. 6;

Fig; 10 is a section taken on another lay shaft substantially on theline Ill-l0 of Fig. 6;

Fig; 11 is a schematic diagram of the gear trains of the modification ofFigs. 5-10,, laid out in a plane; V

Fig. 12 is a schematic diagram of another gear train modification, laidout in a plane;

Fig. 13 is a control diagram applicable to the modification showninFigs; 1-4 inclusive;

Fig. 14 is a control diagram applicable to the 5Q} modification of Figs.5-11 inclusive: and

within a hub 32 having blade sockets 34 and a splined engagement with adrive shaft 36. The blades are mounted within the sockets 34 upon splitthrust bearings 3'! and are adapted to be turned by blade worm gear orwheel sectors 38 journalled on bearings 40 mounted around integral hubbosses 42. A laterally flexible torsion transmitting sleeve 44 splinedto the blade as at 46, and to the blade gear as at 48 is adapted totransmit turning moments between the blade worm gear 38 and blade whilerelieving the gear 38 of stresses resulting from blade deflection inoperation, off alinement from the axes of the retention or thrustbearings 40-. The worm wheels 38 are driven by hour-glass worms earranged parallel to the axis of rotation of the hub. Each of the wormsis provided with bearings 52 maintaining position and alignment of theworm with respect to its mating worrn'wheel and each worm is providedwith a spur gear 54 engaging a common sleeve gear 56 concentric with thepropeller shaft and integrally formed or secured to a propeller pitchchanging sleeve 58.

It will appear from the construction thus described that rotation of thesleeve 58 and its gear 56 relative to the propeller shaft in onedirection or the other will effect changes in pitch of all the blades inunison. It will also appear that if the sleeve 58 be enforced to rotateat the same speed as the propeller shaft that the pitch of all theblades cannot change.

I In order to secure the desired rotation of the sleeve 58 relative tothe propeller shaft to effect changes in pitch or to fix the sleeveagainst rotation relative to the hub, mechanism including planetary geartrains mounted within a housing 59, having forward and rear walls SI and63, is employed to enforce movement of the sleeve relative to or withthe shaft as may be-desired.

For this purpose, the sleeve is provided with a spur gear 60 and theshaft 36 is provided with a power gear 62 keyed thereon. Meshing witheach of the gears 60 and 62 are spur gears 64 and 66 having internalgear teeth 68 and It forming part of planetary gear trains I2 and Hi.The internal gears 68 and I0 mesh with a plurality of planet gears 16and 18 which in turn revolve about sun gears 80 and 82. The planet gears'56 and f8 while relatively rotatable with respect to one another, aremounted upon common shafts 84 carried in a common spider 83.

It will appear from a consideration of the planetary gear trains 12 and14 that upon the sun gears 80 and 82 being locked against rela tiverotation, the spur gears 64 and 60 will rotate in unison and force thesleeve gear 58 to rotate at the same speed as thepower gear 62. However,if there be established relative rotation in one direction or anotherbetween the sun gears 80 and 82, then relative motion between the spurgears 64 and 66 will occur causing relative motion between the sleevegear 68 and the power gear 62, which motion will thereby effect anincrease or decrease in pitch depending upon the direction of relativemovement between the sun gears 80 and 82. In the modification shown, thesun gear 82 is normally fixed against rotation and the sun gear 80 is soarranged that it may be fixed, or driven in either direction at one ofthree different speeds. The sun gear 80 is fixed to a shaft I68 and agear I06, the latter being driven by a gear 94 on a lay shaft I04. Freeto rotate on the shaft I04 are gears 96 and 98 which are jointly 4 orindividually clutchable to the shaft I84 by means of hydraulicallyactuated disc clutches H0 and H2, said units comprising clutch elementsI02 keyed to the shaft I04. A shaft 88, which may be driven at threedifferent speeds as will be described, is provided with a gear 90driving the gear 953 and with a gear 52 driving the gear 98 through areversing idler I56 interposed therebetween. With the shaft 88 notdriven, both clutches HE! and H2 may be locked, thereby locking theshaft I04 from rotation due to locking of the gear train 95, 90, 92, I00and Then, through the gear connection 94, I66, the sun gear is lockedfrom rotation. If the shaft 88 is driven in one direction, regardless ofspeed, locking of either clutch H6 or IIZ will produce turning of thegear 94 and thus of the sun gear 80, in forward or reverse directionswhereby to effect blade pitch changes.

Power may be applied to the shaft 88 for driving the sun gear 86 bycoupling the shaft through a hydraulic disc clutch or other suitablemeans H4 to a gear IIB meshing with the power gear 62. If it be desiredto drive the shaft 88 at a lower speed than that provided by the gearIIS acting through the clutch I14, additional gear trains may beintroduced to provide lower speeds. For this purpose a gear H8, alsomeshing with the power gear 52, may be coupled through a clutch I20 to apinion I22 on a shaft I23 meshing with a gear I24 on shaft 88. In orderto drive the shaft 88 at a still lower speed, gear,

I26, meshing with the power gear 62, may be caused to drive a pinion I28through a selective clutch I30 and to thereby drive a gear I3I on theshaft I23 which then drives the shaft 88 through gears I22 and I24.

By selectively engaging either of clutches II 0 or H2 and any one ofclutches II4, I20 and I30, the pitch of the propeller blades may bevaried in one direction or the other at any one of three speeds. It willalso appear that if clutches H0 and H2 be simultaneously engaged whilethe clutches H4, I20 and I30 are disengaged, the

gears 90, 92, I00 and 98 and 98 will be locked against rotation, therebylocking gear 94, its meshing gear I06 and the sun gear 80. By thismeans, the pitch of the propeller blades may be fixed against change.

During the operation previously described, the sun gear 82 has been heldagainst rotation.

Under circumstances requiring feathering or un-.

Fig. 5, a somewhat different propeller hub structure is shown, thestructural details of which appear in a co-pending application SerialNo.

675,383 filed June 8, 1946. Each of the propeller blades is swivellymounted and provided with a driving train driven by gears 54 which aredriven in unison by a propeller shaft concentric sleeve gear 56. As inthe previous modification, rotation of the sleeve gear relative to thepropeller shaft 36 or hub 32 splined thereto will effect an increase ordecrease in pitch depending on the relative direction of rotation. Bysecuring the sleeve gear 56 against relative rotation with re- 1 As inthe previous modification, it that variation in pitch may be effected byrela 5. spent to the shaft-"afigthe pitch of the propeller blades :is-fixed. As in the previous modification, the sleeve :gear 56 is carriedon a sleeve =58 havagear 60. The drive shaft 86 and the hub 82 splinedthereon is provided with a power gear '62 "keyed or otherwise securedfor rotation with the propeller shaft .36. Meshing with the power gear=62 and the sleeve gear 60 are spur gears 64 and 66 formed externally onthe rims of internal gears 68 and of a pair of similar planetary geartrains 12 and 14. Each 'of these gear trains has planet gears 16 and 18and-sun gears 80 and 8.2. The planet gears 16 and 18 are rotatablerelative to one another but are carried upon a common spider 86. I p

will appear tive rotation of the sun gears 80 and 82., l he sun gears 80and 82 of the planetary sets 12 and 1.4 are provided with control gearsI14 and I16 respectively. p

On a lay shaft I18 spaced from and parallel to the axis of the planetarygear trains 12 and 14 are a pair of gears I80 and I 82 meshing withcontrol gears I14 and I16. Each of the gears I80 and I82' is adapted tobe held against rotation through engagement of hydraulic brakes I84 andI86 which react against the end housing plates I88 and I89 of the casingI90. A third gear -I9I rotatably mounted upon the lay shaft I18 isadapted to be clutched to either gear I80 or I82 through hydraulicclutches I92 and I94 disposed between gearI9I, and I80 and I82respectively.

Mechanism is provided for driving the gear I9'I at two different speedsso that by applying either of the brakes I84 or I86 and actuating one ofthe clutches I92 or I94 so as to couple the unbraked gear of gears I80or I82 to the intermediate gear I9I, movement of the propeller pitchchanging gear sleeve 58 relative to the hub and shaft is effected. Suchgearing is provided on a third rotatable lay shaft I96 having a gear I98journalled thereon meshed with the power gear 62. Through a hydraulicclutch 200, the gear I98 may be coupled to'a drive gear 202 normallyfreely rotatable on'the shaft I96, whi'ch is meshed with theintermediate gear I91 on the lay shaft I18 which drives said gear I9I atone speed. To provide a different speed for rotating the gear 202 fromthe power gear I58, a speed reducing back gear train 204 is arrangedupon an auxiliary spindle 2I2. The back gear train comprises a pinion206 fixed for rotation with gear'l98' and a meshing gear 208 secured toa pinion 2I0, both-rotatable with or on the shaft 2I2. A gear 214 keyedto the shaft I96 and meshing with the pinion 2 I0 completes the backgear train. Through a second clutch 216; the shaft I96 and the gear 2 I4may be coupled-to the gear 202, enforcing drive of the: latter throughthe back gear train at reduced speed.

It will be understood that the various clutches described in the three.modifications herein dis= closed may be of any type capable of carryingthe requisite torque and load requirements. The clutches may consist ofmultiple discs having a1 ternating inner and outer lugs splined to therela= tively rotatable parts. The engagement of the discs is effected byan annular pistonsuch as 220 (Fig. 8) axially movable within an annularcylinder I having port connections to a com duit 223 extendinglongitudinally through the shaft. Where the shaft rotates as does thelay shaft in Fig. 8, additional fluid transfer means 222- are requiredbetween the frame bearing,v 224 6 and the shaft I96. Each of thehydraulic clutches may embody the features of the hydraulic clutchesdisclosed in the previously referred to co-pending application SerialNo. 675,383 filed June 8, 1946.

From the foregoing description, it willbe seen that the pitch of thepropeller blades :may be fixed or varied in either direction at twodifferent speeds. In order to fix pitch, clutches I84 and W6- areapplied. In order to increase pitch, clutch I86 may be applied andclutch I92 'ap-- plied, and in addition one of the clutches 200 or 216depending on whether fast or slow rate of pitch change is desired. Ifpitch decrease is do;- sired, then the brake 184 will be actuated tohold gear I80 and clutch I94 and either one of clutches 200 or 2 I6:will be actuated depending on Whether a fast or slow rate of pitchdecrease is desired.

In the modification shown in Fig. 12, the same general principles areemployed as in the pre- .vious modificationsexcept that the gears are soarranged that pitch is retained fixed by -si-'- multaneous clutching ofthe high and low speed gear trains, to lock them against rotation. Thistrain would be arranged in a housing embracing the propeller shaft inthe same fashion as the other modifications described, and is shown onlyas a schematic diagram since structural arrangements would be of thesame character as in the other embodiments. As shown, the drive shaft 86has keyed thereto a pair of power gears 62 and the pitch changing gearsleeve 58, adapted to be fixed against relative rotation between it andthe shaft 86 to fix pitch, or to be relatively Y rotated in onedirection or the other to effect changes in pitch. Double planetary geartrains 12 and 14 are arranged coaxially with a lay shaft 248. Theinternal gear 10 of the planetary gear train 14 is .provided withexternal gear teeth in mesh with one power gear 62. The internal gear 68of the planet gear train 12 is rovided with external gear teeth 64 whichmesh with the gear formed integrally with the sleeve 58. As previously,the planet gears 16 and 18 of the'two planetary gear trains are freelyrotatable relative to one another but are carried on a common spider86'. The sun gear 82 is secured against rotation, while the sun gear issecured for rotation with a gear 258 mounted on the shaft 240. The gear82 may be driven by an electric motor in. a manner described previously,to allow blade pitch change when the power shaft 36 is not operating.

On an adjacent rotatable lay shaft 260 are ar-' ranged two freelyrotatable gears 262 and 268, the former meshing with the external teeth66 of the planetary 16 while the gear 268 is meshed directly with thepower gear 62. Thus it will be seen that gears 262 and 268 rotate inopposite directions at the same speed so long as the propeller shaft andthe power gear rotate. Through hydraulic: clutches 216 and 212, eithergear 262 or 268 may be clutched to the shaft 268 so as to drive theshaft selectively in either direction. Keyed to the shaft 260, are apinion 214 and gear 216 which in turn mesh with a gear 218 and a pinion288, rotatably mounted upon a third rotatable lay shaft 282. By means ofclutches 284 and 266 either gear 218 or pinion 280 may be clutched tothe shaft 282 so as to. drive a pinion 288 secured to the shaft 2.82 andin mesh with an idler gear 268' freely mounted on shaft 260, the'idlergear driving gear 258 of shaft 2.40 and consequently the sun gear 80. Byactuating either clutch 210 or 2112 depending on. whether a pitchincrease or decrease is desired and upon the actuation of either clutch284 or 286 depending upon whether a fast or slow rate of pitch change isdesired, the sun gear 88 will be rotated in one direction or the otherat one of two rates of speed, which in turn Will drive the pitchchanging sleeve 58 in one direction or the other relative to thepropeller shaft 238.

If it is desired to merely fix the pitch, both of the clutches 218 and212 will be released while both clutches 28B and 284 will besimultaneously engaged. Thus the gear 218 meshed with the pinion 214 andthe pinion 288 meshed with the gear 278 will effectally lock the shaft282 and pinion 288 against rotation and thereby fix the sun gear 88against rotation. Under these circumstances, no pitch change can occur.As in the previous modifications, the lay shafts 248, 268 and 282 aresupported in bearings in end plates 292 and 294 of the gear housing, andprovision is made in the shafts 268 and 282 and their bearings toprovide pressure operating fluid to the various fluid clutches.

Control over the clutches shown in the three described modifications maybe effected by systems such as are shown in Figs. 13, 14 and 15. Asshown in Fig. 13 wherein a control system for the modification of Figs.1-4 appears, electromagnetically operated fluid valves are provided, onefor each of the clutches IIO, H2, H4, I28 and I38. Each valve isprovided with a balanced piston 388 actuated by a solenoid 3I2. Fluidunder pressure is supplied from a gear pump 3I4 deriving fluid from asump 3H5, the fluid being introduced into the valve casings between thepiston ends SIB and. 328 of each of the balanced valves 3I8 through aconduit 3I9. By shiftingany valve to the position shown at A, thepressure fluid is immediately fed to a conduit leading to the selectedclutch. Upon return of the valve to its inactive (fuil line) position,the clutch pressure is relieved through a conduit MI and the fluid isreturned to the sump. Since it is necessary to actuate two clutchessimultaneously to effect no pitch change or pitch increase or decreaseat one of the three speeds provided, manual' contactors are provided toeffect closure of the proper solenoid circuits for each possibleselection. The contactor simultaneously actuates clutches H8 and M2 tofix propeller pitch. Contactors 324, 328 and 332 each actuatesimultaneously clutch H8 and one of the clutches II4, I28 or I38depending on whether high, medium or low speed pitch decrease is desired(it being assumed that clutch H8 causes rotation in a decrease pitchdirection and clutch I I2 in a pitch increase direction). Similarly,contactors 825, 938 and simultaneously actuate clutch H2 and one ofclutches i it, i 28 or I38 to provide any one of the three speeds ofpitch increase. It will be understood that any form of interlock may beemployed in order to prevent the actuation of more than one contactor atany one time, in order to safeguard the apparatus against any possiblejamming.

In Fig. 14, six valves are employed for actuating the clutches I84, I82,I84, I86, 288 and 2I6 of the modification shown in Figs. through 11. Inthis modification, for fixing the pitch, the clutches Hi5 and I84require simultaneous actuation. For varying the pitch, a combination ofthree clutches must be actuated simultaneously. It is assumed thatclutches I 84 and I94 operate to effect pitch decrease, and I86 and I92operate to effect pitch increase. Contactor 344 actuates clutches I84and I88 simultaneously to fix pitch; Contactor 346 actuates clutchesI84, I94 and 2I6 to provide rapid pitch decrease. Contactor 348 actuatesclutches I86, I92, and 288 to increase pitch at low speed. Contactor 358actuates clutches I84, I84 and 288 to effect a low rate of pitchdecrease and contactor 352 actuates clutches I86, I92 and 2I6 to providea high rate of pitch increase.

In Fig. 15 a four valve arrangement is shown for actuating the clutches278, 212, 284, and 286 of the modification shown in Fig. 12. In thisarrangement, pitch is fixed by actuating clutches 284 and 286simultaneously by means of contactor 368. Clutch 288 in combination withclutch 218, actuated by contactor 362 effects a high rate of pitchdecrease. Contactor 364 actuates clutches 2'18 and 294 resulting in alow rate of pitch decrease. Contactor 368 actuates clutches 288 and 212resulting in a high rate of pitch increase. Contactor 888 simultaneouslyactuates clutches 272 and 284 to effect a low rate of pitch increase. Itshould be understood that the switch units 322334, 344-352 and 368388 ina propeller installation would be operated by automatic control devicessuch as regulators or governors, as well as by manual selection attimes. Also, limit switches to limit high and low governed pitch,feathering and reverse pitch would be embodied in the propeller, thesedevices being arranged to cooperate with manual and automatic controlsto coordinate propeller operation within theseveral regimes of operationwhich .are desired.

Though several embodiments illustrating the invention have been shownand described, it is to be understood that the invention may be appliedin other and various forms. Changes may be made in the arrangements,without departing from the spirit of the invention. Reference shouldbehad to the appended claims for definitions of the limits of theinvention.

What is claimed is:

1. In a variable pitch propeller, a hub, blades swivelled therein forpitch change, a drive shaft, a sleeve on said drive shaft, meansresponsive to the relative rotation between said sleeve and shaft foreffecting pitch change, a pair of planetary gear trains each havingcoaxial gears and planet gears interposed and having a common planetcarrier, a coaxial gear of each planetary geared to said sleeve andshaft respectively, means for fixing one of the remaining coaxial gears,and means for holding, or driving the other remaining coaxial gear atdifferent speeds and in different directions to fix, or increase ordecrease pitch at different speeds, said means for driving the othergear including means for deriving driving torque from the drive shaft atthree different speeds and in either direction.

2. In a variable pitch propeller, a hub, blades swivelled therein forpitch change, a drive shaft, asleeve on said drive shaft, meansresponsive to the relative rotation between said sleeve and shaft foreffecting pitch change, a pair of planetary gear trains each havingcoaxial gears and planet gears interposed and having a common planetcarrier, a coaxial gear of each planetary geared to said sleeve andshaft respectively, means for fixing one of the remaining coaxial gears,and means for holding, or driving the other remaining coaxial gear atdifferent speeds and in different directions to fix, or increase ordecrease pitch at different speeds, said means for driving the othergear including means for deriving driving torque from the shaft at twodifferent speeds and in either direction.

3. In a variable pitch propeller, a hub, blades swivelled therein forpitch change, a drive shaft, a sleeve on said drive shaft, meansresponsive to the relative rotation between said sleeve and shaft foreffecting pitch change, a pair of planetary gear trains laterally spacedwith respect to the shaft axis each having coaxial gears and planetgears interposed and planet carrier means for said planet gears, meansfor pairing an element of each of said planetary gear trains forconcomitant rotation, means for gearing two elements of said planetarygear trains to said sleeve and shaft respectively, mean for fixing oneof the remaining elements, and means for holding, or driving the otherremaining element at different speeds and in different directions tofix, or increase or decrease pitch at different speeds,

said means for driving the other element includingmeans for derivingdriving torque from the drive shaft at three different speeds and ineither direction.

4. In a variable pitch propeller, a propeller shaft, a hub, bladesswivelled in said hub for pitch variation, a sleeve around said shaftand adapted for relative rotation, means interposed between said sleeveand blades for effecting changes of pitch upon rotation of said sleeverelative to said shaft, a plurality of lay shafts arranged about saidpropeller shaft, planetary gear trains on one of said lay shafts, gearedto said sleeve and said propeller shaft, and gearing on the remaininglay shafts for coupling an element of one of said planetaries to saidpropeller shaft for deriving power therefrom, said gearing having meansfor providing two directions of motion of said element at a plurality ofspeeds.

5. In a variable pitch propeller, a propeller shaft, a hub, bladesswivelled in said hub for pitch variation, a sleeve around said shaftand adapted for relative rotation, means interposed between said sleeveand blades for efiecting changes of pitch upon rotation of said sleeverelative to said shaft, a plurality of lay shafts arranged about saidpropeller shaft, planetary gear trains on one of said lay shafts, gearedto said sleeve and said propeller shaft, gearing on the remaining layshafts for coupling an element of one of said planetaries to saidpropeller shaft for deriving power therefrom, said gearing having meansfor providing two directions of motion of said element at a plurality ofspeeds, means for uncoupling said gearing from said propeller shaft, andmeans for locking said gearing against rotation by actuatingsimultaneously said means for providing motion at two different speeds.

6. In a variable pitch propeller, a hub, blades swivelled therein forpitch change, a drive shaft, a sleeve on said drive shaft, meansresponsive to the relative rotation between said sleeve and shaft foreffecting pitch change, a pair of plane tary gear trains each havingcoaxial gears and planet gears interposed and having a common planetcarrier, a coaxial gear of each planetary geared to said sleeve andshaft respectively, means for fixingone of the remaining coaxial gears,and means for holding, or driving the other remaining coaxial gear ineither direction to fix, or increase or decrease pitch, said means fordriving the other gear including means for derivin driving power fromthe drive shaft.

CHARLES W. CHILLSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,314,025 Waseige Mar. 16, 19432,370,675 McCoy Mar. 6, 1945 2,437,188 Forsyth Mar. 2, 1948 2,455,000Forsyth Nov. 30, 1948 FOREIGN PATENTS Number Country Date 840,491 Francea Jan. 16, 1939

